Reversing clutches with follow-up valve

ABSTRACT

A reversing gear, primarily for boat engines, comprising a pair of coaxial, counter-rotating drive elements, and a driven element accommodated in the space between said drive elements and mounted for axial displacement so as to be engaged with either of, and disengaged from, said drive elements. The driven element is carried by a plunger the end portions of which are received in cylinder chambers provided in said drive elements and communicating, via ducts in the drive shaft, with pressure fluid supply and drainage ports controlled by an axially displaceable slide valve so that a servo effect is obtained when the slide valve is displaced relative to the shaft which is thereby itself caused to move axially, together with the driven element, relative to the slide valve and the drive elements, respectively.

Andersen 1 3,710,907 [451 Jan. 16,1973

REVERSING CLUTCHES WITH FOLLOW-UP VALVE Ellif Andersen, J'yderup,Denmark Motortabrlken Bukh A/G, Kalundborg, Denmark Filed: Dec. 30, 1971Appl. No.: 214,045

Inventor:

Assignee:

Foreign Application Priority Data Jan. 6, 1971 Denmark ..4l/7l US. Cl...192/87.l7, 192/87.19, 192/86, l37/625.63

Int. Cl ..Fl6d 25/10 Field of Search ..l92/86, 87.17, 87.18, 87.19

References Cited UNITED STATES PATENTS 8/1940 Halford ..l92/87.l9 6/1952Armitage et al ..l92/87.l7

Primary ExaminerBenjamin W. Wyche Attorney-William E. Schuyler, Jr. ctal.

[57] ABSTRACT A reversing gear, primarily for boat engines, comprising apair of coaxial, counter-rotating drive elements, and a driven elementaccommodated in the space between said drive elements and mounted foraxial displacement so as to be engaged with either of, and disengagedfrom, said drive elements. The driven element is carried by a plungerthe end portions of which are received in cylinder chambers provided insaid drive elements and communicating, via ducts in the drive shaft,with pressure fluid supply and drainage ports controlled by an axiallydisplaceable slide valve so that a servo effect is obtained when theslide valve is displaced relative to the shaft which is thereby itselfcaused to move axially, together with the driven element, relative tothe slide valve and the drive elements, respectively.

1 Claim, 3 Drawing Figures REVERSING CLUTCHES WITH FOLLOW-UP VALVE Theinvention relates to a hydraulically operated reversing gear intendedparticularly, but not exclusively, for boat engines and comprising twocoaxial driving elements rotating in opposite directions, and anassociated driven element that is connected to the driven shaft of thegear and is located between the driving elements so as to be broughtinto driving engagement with either of these driving elements by anaxial displacement relative thereto.

It is an object of the invention to provide a particu larly compact andsturdy design of such a reversing gear in which the displacementnecessary for a reversal of the rotational movement of the driven shaftshall further be possible in a simple manner.

The reversing gear according to the invention is characterized in thatthe driving elements are secured against axial displacement and form apair of cylinder chambers that are open where facing each other foraccommodating the end portions of a plunger that is rigidly connected tothe driven shaft and, on its central portion, carries the driven elementand which is axially displaceable in conjunction with this element andthe driven shaft that contains a pair of hydraulic fluid ducts eachcommunicating with one of the cylinder chambers and having radial inletand outlet ports lying outside the cylinder chambers and being spacedaxially apart in a slide face for an annular slide valve, that surroundsthe driven shaft and is displaceable in its axial direction so as toconnect either of the ports to the hydraulic fluid pressure pipe whilethe other port is opened for drainage of fluid of the associatedcylinder chamber.

For changing the rotation of the driven shaft, all what is needed is anaxial displacement of the annular slide valve for controlling the flowof the hydraulic fluid to and from the two cylinder chambers. In itscenter position, the slide valve keeps both ports closed so that bothcylinder chambers are under equal pressure which, in turn, has theeffect of keeping the plunger and the driven element in a centerposition in which this element is out of engagement with the two drivingelements. If the slide valve is displaced out of its center position, itwill provide access for the hydraulic pressure fluid to one of thecylinder chambers while the other one is drained. This causes theplunger together with the driven element to be displaced in acorresponding manner so that the driven element is brought intoengagement with one or the other of the driving elements. The drivenshaft participates in this displacement and is thereby moved axially inrelation to the slide valve, now stationary, so that the inlet andoutlet ports are again closed or substantially closed by the slidevalve.

Consequently it is possible to utilize the hydraulic pressure fluid notmerely for displacing the plunger and the driven element that is rigidlyconnected thereto, but also for maintaining the plunger and, thereby,the driven element in the two extreme positions as well as in the centerposition.

The individual components of the gearmay, without detriment to itsfunction, be manufactured with relatively rough tolerances and the riskof an undesired locking or jamming of the gear in one or the otherposition can beregarded as precluded under normal conditions since thefunction does not depend on return springs which, as experience hasshown, 7 can be damaged in use.

Further details and advantages of the reversing gear according to theinvention will become apparent from the following description of anembodiment with reference to the accompanying drawing, in which FIG. 1is a vertical longitudinal section through this embodiment of thereversing gear according to the invention with the driven element in itscenter position, that is to say disengaged from the driving elements,and

FIGS. 2 and 3 partial sections similar to FIG. 1 with the driven elementengaged with one or the other of the driving elements, respectively.

As illustrated, the reversing gear has a box-shaped casing 1 with avertical partition 2 and with bearings 3 for a drive shaft 4 and adriven shaft 5. Fixed to the drive shaft 4 are two gear wheels 6 and 7which are directly and by means of an intermediate gear wheel (notshown), respectively, each in engagement with one of two bowl-shapedfriction drive elements 8 and 9 which, consequently, rotate in oppositedirections. Driving elements 8 and 9 are supported in casing l in such away that they cannot be axially displaced.

A corresponding driven friction element 10 is carried by a collar orflange 1 1 on the center part of a plunger 12 which is integral with thedriven shafts and which, with its end portions, is located insidecylinder chambers l3 and 14 formed by the bowl-shaped friction elements8 and 9.

Shaft 5 contains longitudinal ducts 15 and 16 that connect cylinderchambers 13 and 14 with radial ports 17 and 18 which are axially spacedapart in a slide face surrounded by an annular slide valve 19 that isaxially displaceable on shaft 5 and contains a hydraulic fluid pressurebore 20 terminating in an annular groove 21.

In FIG. 1, the gear is shown in its neutral position in which theplunger 12 and the slide valve 19 are in their respective centerpositions. Hereby, ports 17 and 18 are closed by the slide valve 19 andthe driven element 10 is disengaged from both driving elements 8 and 9.

When it is desired to rotate the driven shaft 5 in the same direction asdrive element 8, slide valve 19 is displaced laterally to the right,that is to say into the position illustrated in FIG. 2. Hereby,communication will be established from hydraulic fluid pressure pipe 20to cylinder chamber 14 via port 18 and duct 16, while cylinder chamber13 communicates with the draining orifice via duct 15 and port 17.Plunger l2 and, thereby, the driven element 10, will consequently bedisplaced to the right until element 10 comes into engagement withdriving element 8 as shown in FIG. 2. However, the driven shaft 5 and,with it, ports 17 and 18, also participate in this displacementmovement, so

that they, in relation to slide valve 19, again approach the position inwhich both these ports are closed. This situation appears from FIG. 2,in which it is indicated, however, that the two ports are not completelyclosed so that the hydraulic fluid continues to have access to cylinderchamber 14 and is able to drain more or less freely from cylinderchamber 13.

Shifting the gear back into its neutral position is effected by abackward displacement of slide valve 19 into its center position. Thenthe pressure fluid will first be led to cylinder chamber 13 via port 17and duct 5, while fluid is drained freely from cylinder chamber 14.

the displacement movement to the left, both ports 17 and 18 will beclosed by slide valve 19 as shown in FIG. 1 and the gear willConsequently remain in the neutral position. I

Engaging and disengaging the driven element with and from drivingelement 9 is effected in an analogous manner by a lateral displacementto the left of slide valve 19 from its center position shown in FIG. 1.This situation is illustrated in FIG. 3, where cylinder chamber 13 isunder hydraulicfluid pressure, while cylinder chamber 14 is drained moreor less freely via duct 16 and port 18.

I claim:

1. A hydraulically operated reversing gear, comprising a casing, a pairof counter-rotating, coaxial, and axially spaced driving elements whichare held against axial displacement and each present a cylinder chamberhaving an open end towards the space between said elements, a drivenshaft that is journalled for rotation and axial displacement in saidcasing, a

plunger carried by said shaft and held against rotation and axialdisplacement relative thereto, said plunger having its end portionsaccommodated in the cylinder chambers of said driving elements, a drivenelement carried by said plunger between said end portions, and

means for axially displacing said shaft with said plunger and drivenelement between two extreme positions in which said driven element is intorque transmitting engagement with one and the other, respectively, ofsaid driving elements, said displacing means comprising an annular slidevalve that surrounds a slide face on said driven shaft having a pair ofaxially spaced ports which through respective ducts in said shaftcommunicate with one and the other, respectively, of said cylinderchambers, said slide valve having connections for supply and drainage ofhydraulic fluid and being axially displaceable on said slide facebetween two extreme positions in which a respective one of said portscommunicates with the supply connection while the other portcommunicates with the drainage connection.

1. A hydraulically operated reversing gear, comprising a casing, a pairof counter-rotating, coaxial, and axially spaced driving elements whichare held against axial displacement and each present a cylinder chamberhaving an open end towards the space between said elements, a drivenshaft that is journalled for rotation and axial displacement in saidcasing, a plunger carried by said shaft and held against rotation andaxial displacement relative thereto, said plunger having its endportions accommodated in the cylinder chambers of said driving elements,a driven element carried by said plunger between said end portions, andmeans for axially displacing said shaft with said plunger and drivenelement between two extreme positions in which said driven element is intorque transmitting engagement with one and the other, respectively, ofsaid driving elements, said displacing means comprising an annular slidevalve that surrounds a slide face on said driven shaft having a pair ofaxially spaced ports which through respective ducts in said shaftcommunicate with one and the other, respectively, of said cylinderchambers, said slide valve having connections for supply and drainage ofhydraulic fluid and being axially displaceable on said slide facebetween two extreme positions in which a respective one of said portscommunicates with the supply connection while the other portcommunicates with the drainage connection.